Category Archives: Dr. Neil Hammerschlag

Coral Bleaching of the Great Barrier Reef

The following article first appeared on the Research Blog for Dr. Neil Hammerschlag’s Shark Research and Conservation (SRC) Lab website at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science. To learn more about SRC, visit here:, or to learn more about the University’s marine science school, please click here:

By Delaney Reynolds, SRC intern

Coral reefs are some of planet earth’s most spectacular, diverse and important ecosystems. Our planet’s coral reefs provide important shelter, habitats, and a source of food for many different species of marine organisms. They also act as a critical food source to humans, as well a natural barrier to help protect our coastlines from hurricanes and associated storm surges. Sadly, coral reefs face growing risks including the possibility of extinction from a variety of stresses that leads to coral bleaching.

Coral Bleaching

Figure 1: Coral from which the zooxanthellae has been expelled, causing it to turn white (Image Source:

Coral bleaching is the process in which zooxanthellae, algae living symbiotically within the coral, are expelled from coral colonies due to a number of factors including an increase in temperature, decrease in pH, exposure to UV radiation, reduced salinity, and bacterial infections. Zooxanthellae provide the coral 30% of its nitrogen and 91% of its carbon needs to the coral host in exchange for a shelter, as well as waste produced by the coral from nitrogen, phosphorus, and carbon dioxide that is required for the algae’s growth (Baird, 2002).

When corals bleach, it effects entire marine communities due to their immense diversity. Fish populations that reside around coral reefs “are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries” (Graham, 2008). Researchers have found that when an ecosystem endures physical coral loss, fish species richness is extremely likely to decline due to their heavy reliance on the coral colony itself (Graham, 2008).

Perhaps the most famous current example of coral bleaching is Australia’s Great Barrier Reef. Scientists have determined that the main cause of Great Barrier Reef coral bleaching is induced thermal stress and that about 90% of the reef has been bleached since 1998 (Baird, 2002). As the corals bleach and temperatures increase, researchers have determined that shark and ray species that live in the area may be vulnerable to these climactic changes.

Exposure of Ecological Groups of GBR Sharks and Rays to Climate Change Factors

Figure 2: Exposure of Ecological Groups of GBR Sharks and Rays to Climate Change Factors. This figure displays the vulnerability different elasmobranch species face due to climate change, as well as the specific effects of climate change that they are vulnerable to, in the specific zones of the Great Barrier Reef. (Image Source: Chin et al. 2010)

Most of the Great Barrier Reef is located on the mid-shelf of the ocean floor, the approximate mid-point between the shallower coast of Australia and the continental shelf where the ocean bottom significantly drops in depth. Researchers found that the mid-shelf is the area where most of the shark species studied reside, while most rays dwell in coastal waters or closer to the continental shelf. It was also found that both areas are the susceptible to rising temperature, increased storm frequency and intensity, increasing acidity, current alterations, and freshwater runoff, all being caused by climate change (Chin, 2010). Based on these findings, researchers have concluded that the areas these elasmobranchs live in should be protected and preserved. Species in these highly vulnerable areas should also be monitored and considered for future conservation actions, as many of the shark species are already experiencing the effects of climate change from some of the aforementioned factors.

Typically, sharks are considered some of the strongest animals on earth, and while they have lived on earth for at least 420 million years, they are slow to adapt. This slowness has impeded their ability to survive in our rapidly changing climate. In the near future it will be common to see some species of marine organisms demonstrate plasticity, the ability to adapt to their changing environment, but other species, such as elasmobranchs, are expected to simply distribute to other habitats in search of cooler waters. Even though sharks are a highly vulnerable species to climate change, they sit at the top of the trophic level in many different niches and, thus, wherever they migrate to, it will be easier for them to find food than it would be for other species such as fish or rays. However, this is most likely only the case for adult sharks as embryos and juvenile sharks may be more vulnerable to increased temperatures. For instance, researchers found that the survival of bamboo shark embryos decreased from 100% at current temperatures to 80% under future ocean temperature scenarios and that the embryonic period was also shortened, not allowing the embryo enough time to develop fully (Rosa, 2014).

To decrease the effects of climate change on coral bleaching, corrective and mitigation measures can be taken. By utilizing green energy sources such as implementing solar power or wind power, walking or biking, and driving electric cars, we can reduce our use of fossil fuels and carbon footprint, thus decreasing the amount of carbon dioxide polluting and warming our atmosphere and oceans. While underwater and not always visible, coral reefs are truly a vital part of our ecosystem and need to be cherished and protected for generations to come.


Baird, A. H., & Marshall, P. A. (2002, July 18). Mortality, growth and reproduction in scleractinian corals following bleaching on the Great Barrier Reef. Retrieved from

Chin, A., Kyne, P. M., Walker, T. I. and McAuley, R. B. (2010), An integrated risk assessment for climate change: analyzing the vulnerability of sharks and rays on Australia’s Great Barrier Reef. Global Change Biology, 16: 1936–1953. doi:10.1111/j.1365-2486.2009.02128.x

Graham, N. A., McClanahan, T. R., MacNeil, M. A., Wilson, S. K., Polunin, N. V., Jennings, S., . . . Sheppard, C. R. (2008, August 27). Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems. Retrieved from

Rosa, R., Baptista, M., Lopes, V. M., Pegado, M. R., Paula, J. R., Trubenbach, K., . . . Repolho, T. (2014, August 13). Early-life exposure to climate change impairs tropical shark survival. Retrieved November 2, 2017, from

“Surreal” Sharks: Learning From The Best

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I am excited to share that the Xploration Awesome Planet episode staring iconic explorer/adventurer Philippe Cousteau and featuring the University of Miami’s Dr. Neil Hammerschlag and his Shark Research and Conservation Program team and Predatory Ecology Lab dropped nationally today on the FOX network.

The episode, shot in Biscayne Bay and the Atlantic waters off Miami, focuses on Dr. Hammerschlag’s research work with sharks, as well as showing that these majestic creatures are not the scary ‘monsters’ depicted in movies and books but are important parts of our planet’s ecosystem.

Aside from my incredible love for sharks, this episode was especially meaningful to me because I was with Philippe and Neil that day (please see the blog that I wrote earlier this year entitled We’re Going to Need a Bigger Boat about this amazing experience by clicking here) and was actually featured in the piece when Philippe interviewed me as I worked to measure one shark and perform various experiments on the boat’s transom.

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As I said during the episode on television today, being with two of my science heroes and the sharks was “surreal.” As I also said, the experience “brings everything we learned in the classroom into the real world and that everything actually matters and that it’s all real.”

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I have been privileged to participate in five University of Miami shark tagging adventures but to be with Dr. Hammerschlag and his team plus Philippe Cousteau from EarthEcho (and on whose International Youth Leadership Council I serve as a member) was something that I will never forget.

Thanks to my school, Palmer Trinity School, and especially the program’s sponsor, Dr. Caroline Hammerschlag, for allowing us to spend the day with the Shark Research and Conservation program to learn from everyone on board, as well as to conduct some super cool hands-on science on these magnificent creatures.

Thanks to Philippe, Neil and the University of Miami’s Rosenstiel School of Marine and Atmospheric Science for an amazing experience and for again showing the world that these incredible creatures are not so scary after all!


We’re Gonna Need A Bigger Boat


I love sharks.

All sorts of sharks. Nurse Sharks, Mako Sharks, Tiger Sharks, Black Tips, Great Whites, Spinners and my favorite, the Crocodile Shark, to name just a few. With ‘Shark Week’ starting tonight on television I’d like to share some of my own shark related adventures with you while also telling you about some of my science heroes as a way to thank them for the amazing work they are doing for our planet.

My fascination with sharks led me to go on my first shark tagging trip with the University of Miami’s Shark Research & Conservation Program (SRC) through my school, Palmer Trinity, when I was in sixth grade. In honor of the fact that Shark Week begins tonight on The Discovery Channel and National Geographic, I’d like to share some incredible pictures from my last shark tagging adventure with you, as well as tell you a bit about the program and the inspiring people who are involved including two of my science heroes.

The SRC Program was created in 2010 by the University of Miami’s Roni Avissar (Professor at and Dean of the UM Rosenstiel School of Marine and Atmospheric Science), Dr. Kenny Broad (Professor at and Chair of UM’s Department of Marine Ecosystems and Society), and Dr. Neil Hammerschlag (Research Assistant Professor in the Department of Marine Ecosystems and Society and Director of the Shark Research & Conservation Program).

The SRC Program allows students and others to learn about these awesome animals up close and to participate in real shark research by testing their nictitating membranes, taking fin clip samples, measuring their length and helping place identification tags on them before they are safely released back into the wild. Between my school’s affiliation with the University of Miami’s SRC and my participation in the University’s Summer Scholars Program I’ve been fortunate to go on three tagging trips, thus far, and each one was absolutely incredible.

Last summer I was far away from South Florida and any thoughts of shark tagging when my family visited Washington D.C.’s many museums and sights. Upon check-in at our hotel we learned that, coincidentally, we were staying across the street from the Headquarters of the National Geographic Society, so naturally we had to add a visit to their offices to our list of things to do. I am sure glad we did because not only were their exhibits great fun to see but it was an incredible surprise to walk around the building’s exterior and come across a huge photograph of Dr. Hammerschlag standing on the sea floor with a 12′ long Tiger Shark swimming above him! I guess even though I was in Washington I was never really that far from the SCS, the sharks or Dr. Hammerschlag’s fine work.12440317_10154620482268265_3583103700094699566_o

Dr. Neil Hammerschlag (in the orange shirt above) is a marine ecologist whose research centers broadly on the behavioral ecology, conservation biology, and the movement ecology of marine predators, primarily sharks. Dr. Hammerschlag’s research includes investigating interactions between sharks and their prey, identifying and learning about shark habitats, studying the impact of urbanization on sharks including the impacts of over fishing on their ecosystems and how sharks respond to climate change. Dr. Hammerschlag is not only an educator and research scientist but also an inventor. For example, using ultra sound technology and techniques that he’s invented he studies pregnant sharks without harming them as would have been the case in the past.160318_123308_191_PalmerTrinity_Web

My most recent shark tagging trip was even more exciting and humbling than is normally the case because not just one, but two, of my science heroes were on board that day. In addition to Dr. Hammerschlag we were joined by none other than Philippe Cousteau who was aboard to film a segment on shark tagging for his Xploration Awesome Planet television show (that’s Philippe in the blue shirt) on FOX and Hulu.

Philippe Cousteau is a world renowned adventurer, educator, filmmaker and author. He is the grandson the iconic Jacques Cousteau and part of perhaps the most important family in all of marine biology. Philippe is also the founder of EarthEcho International which he created to “inspire young people worldwide to act now for a sustainable future.”  I am deeply proud to be a member of Philippe’s inaugural EarthEcho International Youth Council and for him to be with us on my last shark tagging trip was something I will always remember.

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So with Shark Week upon us I hope that you will tune in and watch these cutting edge research educators do their thing.

Dr. Hammerschlag will be premiering in tonight’s Tiger Beach and will also star in Air Jaws: Night Stalker on Tuesday June 28th, both on the Discovery Channel. He will also star (along with the sharks!) in Mega Hammerhead on the National Geographic Channel on June 30th. I also hope that you will tune in and watch Philippe Cousteau’s Nuclear Sharks on the Discovery Channel when it premieres on June 30th.

Allow me to end this post with a special thanks and shout out to a few folks from Palmer Trinity including Dr. Caroline Hammerschlag who was also on the most recent tagging trip my school participated in a couple of months ago. You see, she’s not only an amazing scientist and educator but also a professor at Palmer Trinity and, as I sometimes call her, Mrs. Dr. Hammerschlag, Neil’s wife.

I’m also excited to mention that she; Traci Holstein, our school’s wonderful Science Department Chairperson; and Coach Clint Jones took a small group of Palmer students, myself included, on an absolutely epic Marine Biology Expedition to Hawaii this past Spring. We hiked a volcano, went night diving with Giant Manta Rays, explored nesting sea turtle habitats on black sand beaches and followed Pacific porpoises among other incredible adventures but that, as they say, will be the subject of another post one day.

Thanks to both Palmer and the University of Miami for making such incredible, and indelible, education available and don’t forget to catch some of my heroes on television this week, Shark Week 2016!